As philosopher René Descartes said: "Common sense is the most fairly distributed thing in the world, for each one thinks he is so well endowed with it that even those who are hardest to satisfy in all other matters are not in the habit of desiring more of it than they already have."

Or might I paraphrase: Maybe we're not as smart as we think.

I admit it: When we experienced entrepreneurs see other founders in the news making stupid mistakes, we often roll our eyes, scoff, and wonder, "What else did they expect?" We smugly take pride that we fall into the "common sense group," versus the group of idiots who seem to lack it.

But it might be time to pump the brakes and conduct a reality check before getting quite so self-satisfied.

We're all human, so mistakes are going to happen. And if we're not making business mistakes--or personal ones, for that matter--the amount of passion and opportunity we're leaving on the table is staggering.

That said, I also strongly believe that with experience comes a responsibility to do better. Unless you're fresh out of college, chances are, people won't be particularly sympathetic to stupid mistakes. And such mistakes can be even worse for small-business owners, as our relatively smaller budgets and overextended schedules should be focused on innovation and calculated risks, not cleaning up silly, avoidable messes.

So, let's try a slightly different twist on my "If it don't make dollars, it don't make sense!" mantra and do a little refresher on mistakes that could be avoided with common sense yet are still commonly made--even by well-respected entrepreneurs who have been in the game for a while.

Sloppy Communication

We've got to start with this one, as communication, and lack thereof, is the root of so many problems. None of these really need explaining. Rather, simply use the checklist to check yourself! If you're like me, you've made one, if not more, of these rookie gaffes, despite knowing better. Which are you guilty of?

Not having taken a moment to double-check that your email is replying to a subset, versus an entire group, of recipients.

Sending an email when a call would have been more appropriate, or calling someone when simply dropping the issue would have been more prudent.

Having copied and pasted to save time but left in old details not intended for the new recipient or misspelled a name.

Having mumbled "*!$*#!" after a call, only to realize that you hadn't actually hung up the phone.

Checking your phone or sending texts like a teenager, when you should have been listening and respecting the time of whomever you were meeting with.

Gossiping about someone only to have him walk by and overhear you.

Speaking about client information in the bathroom or elevator.

Assuming your mike was off during downtime in an interview, when you know damn well there's no such thing.

Administrative Errors

Same idea, just focusing on the administrative tasks that if underappreciated, can quickly move from mundane to monstrous! Have you made any of these little mistakes (with big impacts)?

Misplacing paperwork or receipts and then having to scramble to find them at audit, business-tax, or raising-capital time.

Missing a flight because you didn't leave enough time to get to the airport, or worse, read your itinerary wrong.

Forgetting to respond to a critical email or voice mail that you had flagged to "deal with later."

Getting so dependent on that colleague who's an XYZ whiz that you didn't get her to document the basics of her process or identify another person to serve as backup. Then the whiz was unexpectedly out, and you were caught in a lurch.

Missing the opportunity to submit an essential proposal because you waited until the last minute, only to find out that the system crashed because it got overwhelmed by fellow procrastinators.

Time to fess up! I know that I've only scratched the surface on the rookie mistakes that seasoned entrepreneurs get careless about and still make. Let me know your additional thoughts.